Conventional silicone rubber compositions were typically loaded with such fillers as crystalline silica and fused silica. Since these silica fillers contained ionic impurities, they had a purity problem for utility in the silicone rubber compositions intended for forming protective coats on electronic and electric parts. Further, silicone rubber compositions could not be loaded with large amounts of silica fillers partly because silica tend to invite a lowering of flow due to its configurational factor, imposing a certain limit on the loading and partly because separation often occurs between the silica filler and the resin component due to relatively large particle size. For these reasons, the conventional silicone rubber compositions were not regarded optimum as protective coating compositions for electronic and electric parts.